First Steps: Starting and Stopping ROOT

• Overview
• The Lesson
• Summary

Overview

The Lesson

Not to be too ambitious in the first session, type:-

You can type two sorts of input into ROOT, or any application, such as MINFAST, that is based on ROOT:-

• ROOT commands such as .q. These are always preceded with a dot. We shall introduce a few of the more common ones as we go along, but if you want to see the full list then take a look at:-

  CINT Commands

• C++ statements. CINT can cope with most C++ statements although it cannot currently handle a few advanced ones such as certain complex template statements. However, it can deal with everything the beginner needs so is a good tool to learn the language. C++ is a very poor interactive command language and so CINT permits some shortcuts that make life easier. Of course this is counter productive if you are trying to learn the language so, for the most part, these extensions should be avoided.

ROOT uses the VMS/tcsh style command line recall. You can press up arrow repeatedly to scroll up to recall previous commands and then use the left and right arrows to position within the command before editing and re-issuing it.

The ROOT tutorial Starting an Interactive Session explains how it is possible to customise ROOT by editing a set of initialisation and termination script files in much the same way as the .cshrc file is used to customise a csh session.

Summary

• Typing:- root should run ROOT. If it doesn't check $ROOTSYS is defined and that $ROOTSYS/bin is in your path.
• ROOT commands start with a dot. The command .q quits ROOT. The full list is CINT Commands
• ROOT include the CINT C/C++ Interpreter which means that C++ commands can be typed directly into ROOT which is a great way to learn C++, but avoid those shortcuts.
• ROOT includes the VMS/tcsh command line recall system.